Abstract: Methods and apparatus for maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One apparatus includes an optical source coupled to provide an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal. A processor is coupled to compute each of an AC component and a DC component of the optical signal from the same digitally sampled signal. A feedback control is coupled to vary at least one of the DC bias and the AC bias in accordance with a difference between a pre-determined value and a ratio of the AC and DC components.

Abstract: Methods and apparatus for maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One apparatus includes an optical source coupled to provide an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal. A processor is coupled to compute each of an AC component and a DC component of the optical signal from the same digitally sampled signal. A feedback control is coupled to vary at least one of the DC bias and the AC bias in accordance with a difference between a pre-determined value and a ratio of the AC and DC components.

Abstract: Methods and apparatus related to maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One method includes the steps of detecting the AC and DC components of an optical signal having a pilot tone signal. An amplitude of the pilot tone signal is varied in accordance with a difference between a pre-determined value and a ratio of the AC and DC components. Another method includes the step of generating an optical signal in accordance with a DC bias and an AC bias corresponding to a pilot tone signal. The AC and DC components of the optical signal are detected. At least one of the DC bias and the AC bias is varied in accordance with a difference between a pre-determined value and a ratio of the AC and DC components. An apparatus includes an optical source providing an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal.

Abstract: Apparatus for recording data by means of a beam of radiation on a recording medium which upon exposure to the beam undergoes optically detectable changes in the form of pits, which apparatus includes means for reducing the beam intensity as a result of pit initiation thereby forming more accurate pits.

Abstract: A central station system in which the central station is normally connected to one or more remotely located bridging points by a dedicated communication path, each bridging point having a plurality of output ports to which one or more remote station devices are connected. In response to address signals generated by the central station, abridging point connects an identified output port to the dedicated communication path to allow communication between the associated remote stations and the central station. All other output ports are electrically isolated from the dedicated communication path. In the event of failure of the dedicated communication path, apparatus is provided for establishing an alternate communication path through the commercial telephone network. The system is highly immune to tampering and other forms of failure because of automatic decision-making capabilities of the bridging point and other features of the apparatus.